A review on predicting critical collapse pressure of flexible risers for ultra-deep oil and gas production

Abstract

Flexible riser is a key enabler for the oil and gas production in ultra-deep water which transports production fluids between floating production systems and subsea wells. As oil and production heads to water depths in excess of 3000 m, high hydrostatic pressure has been one primary challenge facing the riser operators. Excessive hydrostatic pressure may cause collapse failure of flexible risers and thus predicting the critical collapse pressure is of significant importance to their anti-collapse design. Collapse is a complex phenomenon related to the material properties, the geometry of the pipe and its overall surface topography. Those factors make the prediction of critical pressure of flexible risers challenging. Related prediction approaches of collapse pressure of flexible risers have been developed for decades, yet a comprehensive review of their predictive capabilities, efficiency and drawbacks is lacking. This paper reviews the recent advances on collapse studies of flexible risers and highlights the gaps in existing prediction methods, aiming to facilitate the current anti-collapse design of flexible risers and provide a baseline for their future utilization in deeper water expansion.

Review of Composite Marine Risers for Deep-Water Applications: Design, Development and Mechanics

“…Since marine risers are tubular structures with varied segments, the experimental tests on composite risers were conducted at microscale levels (on composite materials) [257][258][259] and at macroscale levels (on composite risers with composite tubes) [47,80,307,308], which are benchmarked against those of marine steel risers, such as steel catenary risers [35,286]. It is also crucial to test the failure in risers, as research on carbon-fibre-reinforced composite risers have revealed failure mechanisms [59][60][61][62][63] linked to various loading scenarios [131,134,187,195]. Previous experimental studies on composite risers were based on scale-dependent methods of analysis, as tabulated in Table 6.…”

“…However, risers are affected by vibrations and thus require tensioners designed for the control of marine risers [56][57][58]. Different failure modes have also been recorded on marine risers [59][60][61][62][63][64]. Additional riser functions, depending on the application, include: conveying fluids between the wells and the floating, production and storage (FPS) units.…”

Curvature effect on wet collapse behaviours of flexible risers subjected to hydro-static pressure

“…To reduce the computational cost, simplified FE models were developed as an alternative strategy (Li et al 2018). One common simplification is to replace the self-interlocking layers with equivalent tubes.…”

Sealing Performance Analysis of an End Fitting for Marine Unbonded Flexible Pipes Based on Hydraulic-Thermal Finite Element Modeling

“…In addition, a number of studies have focused on the mechanical behavior of flexible pipe, such as the instability of the armor wire [17], the collapse of the carcass layers [18], and fatigue reliability analysis [19]. Although the sealing behavior of the end fitting is unlike the mechanical behavior of the flexible pipe body or the layers inside the end fitting, which have been extensively investigated [8,20], there has been relatively little research on the sealing performance of the end fittings themselves.…”